Archived Bad Shudder

[Tim Galyean]

Please help,



I have a bad shudder/ buck that developes at between 1700 and 2000 rpms when I go to hold on the accelerator to cruise, I took it to a guy two days ago that has a dyno at his house and we could not get it to happen on the dyno. See sig. for list of mods.

It started doing this the day after I replaced the throttle cable, wich was also the day after I drag raced it and had a very hard start at the line. I have checked the springs on the pump, and they are all there and seem to be working fine. Fuel filter has been changed also. It is very hard to determine if the shudder is fuel, or drivetrain induced. I thought that I had a broken drivers side motor mount, but it was fine, and I replaced it any way.

I am begining to run out of Ideas.

 

[y-knot]

I don't know what type on transmission you have, nothing in your sig for info, but it sounds an awlfull lot like a slipping tc in an automatic?

 

[Tim Galyean]

NV4500 5 spd.

 

[Extreme1]

It started right after the throttle cable replacement or did it work OK for a while?

 

[Tim Galyean]

Yes, I did start after the throttle cable replacement. Last night I put some stiffer return springs on, and it still did it. I did learn one thing last night while driving it. Before when it would start to shudder and buck I would let out of the pedal and it would stop, last night I got in the pedal and it worked its way out. I inspected the driveline also last night. The shudder is always in 4th or 5th gear, mostly 5th gear when the engine is under the greatest load, and when I go to steady out the pedal, or slowly get out of it. Engine has good power, no noises. Could it be possible that the govener is screwed up?

 

[Rams-n-Hogs]

When my clutch got weak, (after the #11 went in), it slipped in 4th and 5th gear. It didn't shudder, but I replaced it as soon as I noticed it was slipping. Don't know if that helps or not, but it's a thought. Good luck.



Jim

 

[DTullis]

On my 94 model 2500 the Chrysler dealer damaged the pump changing the throttle cable.



Dealer denies that, of course. I took the truck to Cummins, and they repaired the pump. They reported replacing the rack--I believe that is essentially the throttle which is connected to the throttle cable.



Cummins mechanic told me it was possible to damage the rack while changing the throttle.



Hope that is not your problem. Cummins charged $1100 for pump repair plus $600 to remove/reinstall the pump.



dont

 

[Extreme1]

I don't think you could easily damage the pump internal parts unless you removed the lever from the pump because there is a stop to keep it from traveling too far. (DTullis-this must be what happened on yours).



There is also a return spring on the



What RPM does this happen at? If below 1500 RPM, downshift.



Is the "gas" pedal giving the pump lever full travel? (You'll need help to see). Adjust it so you are getting full travel and have some slack at idle.